1. Field of the Invention
The present invention relates to a relay having a fuse fixedly and directly connected to the relay.
2. Description of the Background Art
More and more electronic devices are mounted on vehicles to enhance fuel economy, anti-pollution measures, drivability, comfortableness in an interior space, etc. Thus, there has been an increase in the number of relays and fuses that are provided in a vehicle fuse box in order to control and protect electrical components. As such, the vehicle fuse boxes become increasingly larger and more complex.
A fuse protects a circuit against damage caused by a short circuit or overcurrent. The link in the fuse will melt and burn in half to stop excess current and further circuit damage. A relay is an electrically operated switch. It allows a small dash switch to control another circuit by remote control, whereby the control comes from a distant point in the circuit.
FIG. 1 is an illustration of a conventional vehicle fuse box 1 that has a plurality of fuse receptacles 3 and relay receptacles 5 for receiving fuses 7 and relays 9, respectively, therein. As can be appreciated, because of the increasing electrical complexity of modern vehicles, the fuse box 1, as noted above, becomes increasingly larger.
DE3209915 and U.S. Pat. No. 6,320,486 each disclose, with reference to FIGS. 2 and 3, respectively, a relay 11 that has two additional connector tabs 13, 15 for removably receiving a melt plugable fuse 17. The arrangements shown in FIGS. 2 and 3 reduce the size of the conventional fuse box 1 because the fuse 17 is able to be plugged directly onto the relay 11, and thus the number of fuse receptacles 3 can be reduced. However, because the relay 11 is designed to use conventional type melt plugable fuses 17, a housing (not shown) of the relay 11 must take into consideration the dimensions of the fuse 17, and thus, a size of the relay 11 is in fact larger than conventional relays 9.
More importantly, because the melt plugable fuses 17 are inserted into the connector tabs 13, 15, heat is generated at contact points 19. In addition, because of current, the contact points 19 relax and degrade and therefore, even more heat is generated. Typically, approximately 1–1.5 watts of heat can be generated at each contact point.
For example, a typical vehicle fuse box 1 has approximately 20 relays and 20 fuses, whereby the fuses each have two contact points and the relays each have 4 contact points. Thus, there are 120 contact points that can generate 120–180 watts of heat. Because of the design of the relay 11 of the prior art, as shown in FIGS. 2 and 3, the generated heat is even more so concentrated in a smaller area on a fuse box than the conventional fuse box 1.
Furthermore, the prior art devices are prone to operator error. For example, if an operator inserts a 40 amp fuse into relay that is rated for 20 amps, the wrongly inserted fuse provides no protection for the relay or the circuit elements associated therewith, which can thus lead to the relay igniting and burning.